1. Field of the Invention
The present invention is generally related to a non-woven, flame resistant fabric and coveralls made from such fabric.
2. Description of the Prior Art
Prior art combat uniform fabrics are woven from yarns made from a staple blend of cotton and nylon fiber. This fiber selection primarily supports dyeing and printing using a combination of acid and vat dyes to impart a camouflage pattern providing both visual and near infrared camouflage protection. This cotton and nylon fiber blend yarn, in combination with a lightweight, thin fabric construction, has consistently provided protection, comfort, durability, and UV resistance for U.S. military service personnel for more than twenty years. Many attempts were made to integrate flame and thermal protection into the aforementioned cotton and nylon fiber blend with little success. Such attempts to integrate flame and thermal protection into the this cotton and nylon fiber blend include fibers, fiber blends and functional finishes such as BASOFIL® flame resistant fiber, Flame Retardant Treated (FRT) cotton, FRT cotton/nylon, FRT TENCEL® fibers, FRT cotton/KEVLAR® para-aramid synthetic fiber/nylon, carbonized rayon/NOMEX® meta-aramid synthetic fiber, KEVLAR® para-aramid synthetic fiber/FR rayon, NOMEX® meta-aramid synthetic fiber/FR rayon, PBI® polybenzimidazole fiber and PBI® polybenzimidazole fiber/FRT cotton. However, many of the inherently flame resistant fibers were eliminated for use in a homogeneous fabric due to their high cost and the requirement for visual and near infrared camouflage. The high polymer orientation of the aramids and PBI, for example, contributes to their flame resistance, but also reduces or eliminates their ability to be dyed with traditional dyestuffs due to the lack of chemical dye sites. Some of these materials may achieve coloration by pigment injection in solution form, but their versatility is limited. Aramid blends are dyed and camouflage-printed using proprietary technology that significantly increases the final cost of the finished fabric. Still prized for their inherent flame resistance, some of these fibers were blended with low cost fibers to enhance the overall flame resistance of the fabric. Flame retardant rayon, which is inherently flame resistant rather than flame retardant treated, was blended with the aramids in 60/40 and 35/65 percent blend ratios, but these materials fell short of the desired fabric strength and the camouflage print demonstrated poor colorfastness.
Another prior art fiber is flame-retardant cotton. Flame-retardant treated cotton has long been the industry standard for use in low cost flame resistant industrial work wear. However, the most commonly used flame-retardant treated cotton, INDURA® flame retardant treated cotton fabrics, adds 20 percent to the weight of the fabric. Flame-retardant treated cotton was blended with nylon in 88/12 percent blend ratios, wherein the nylon was added to improve strength. While the addition of the nylon did not negatively impact the flame resistance, a heavier weight fabric of 11 ounces/yard was required to achieve relatively acceptable breaking and tearing strengths. Flame-retardant treated cotton was also blended with KEVLAR® para-aramid synthetic fiber consisting of poly-paraphenylene terephthalamide and nylon to enhance flame resistance and improve abrasion resistance in a 58/27/15 percent blend ratio. While the KEVLAR® synthetic fiber was the strongest of the three fibers, it occupied less than 50 percent of the total material composition to reduce costs and therefore, the strength of the fabric was determined by the lower strength cotton. In addition, the high end and pick count required to anchor the KEVLAR® synthetic fiber detrimentally reduced the fabric tearing strength to three pounds in the warp and filling directions. PBI® polybenzimidazole fiber was blended with flame-retardant treated cotton in 20/80 percent blend ratio in 5.0 and 6.6 ounce/yard2 weights, however, the performance characteristics were reflective of the predominate fiber, which was, cotton.
BASOFIL® non-woven fabric fiber demonstrated low fiber tenacity and corresponding developmental efforts were directed toward insulation, knitted headwear and hand wear applications wherein high strength was not a critical factor. Blends of carbonized rayon and NOMEX® synthetic fiber consisting of aromatic polyamide polymer were also investigated and, while they demonstrated good strength performance, they could not be dyed and camouflage printed. Flame-retardant treated TENCEL® fibers demonstrated good strength but the camouflage print design demonstrated poor colorfastness performance.
Core spun yarns were also investigated and developed with the primary intent of manufacturing a yarn that has a high strength, inherently flame resistant core, and low cost readily camouflage printable sheath fiber. The best performing material combination was a cotton sheath, KEVLAR® synthetic fiber core yarn. However, these materials did not achieve the required strength because only the KEVLAR® synthetic fiber core and not the sheath contributed to the fabric strength.
While all of the developmental materials investigated met the fabric flame resistance goals (ASTM D 6413; 2.0 seconds, maximum after flame; 25.0 seconds, maximum after glow; 4.0 inches maximum char length), these materials did not achieve the required strength and other performance requirements such as colorfastness of the camouflage print design.
What is needed is a new and improved non-woven, flame resistant garment.